Process for producing a polymer by polymerization of a monomer having an ethylenic double bond

ABSTRACT

A process for producing a polymer by polymerizing in a polymerization vessel a monomer having an ethylenic double bond is provided. In this process, the polymerization vessel has a polymer scale preventive coating film on its inner wall surfaces and other surfaces with which the monomer comes into contact during polymerization. The coating film is formed by coating a coating liquid containing (A) a compound selected from the group consisting of an aromatic compound having 5 or more conjugated π bonds and a heterocyclic compound having 5 or more conjugated π bonds, and (B) a compound selected from the group consisting of an inorganic colloid, a chelate reagent, a metal compound that produces a metal ion capable of forming a complex having at least two coordination numbers, and an acid; the coating liquid being coated by means of steam as a carrier. This process can shorten the time for forming coating films of scale preventive agents to improve productivity, can improve the effect of preventing polymer scales, can make colored particles less which mix into polymer products, can lessen fish eyes and initial discoloring of formed products and can improve the quality of polymeric products and their formed or molded products.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a process for producing a polymer bypolymerizing in a polymerization vessel a monomer having an ethylenicdouble bond, and particularly a process that can prevent polymer scalesfrom adhering to polymerization vessel inner wall surfaces and othersand can produce polymers having a good quality.

2. Description of the Prior Arts

As known in processes for producing polymers by polymerizing monomers inpolymerization vessels, there is a problem that polymers may adhere topolymerization vessel inner wall surfaces and others in the form ofscales.

Such polymer scales having adhered to polymerization vessel inner wallsurfaces and others may cause a decrease in yield of polymers, adecrease in cooling capacity of polymerization vessels, and a loweringof product quality when polymer scales having adhered come off to mixinto polymer products, and also may bring about a disadvantage that muchlabor and time must be taken to remove the polymer scales.

Moreover, since the polymer scales contain unreacted monomers, there isa possibility that operators are exposed to them to cause physicaldisorder.

Accordingly, in the polymerization of monomers having ethylenic doublebonds, in order to prevent polymer scales from adhering topolymerization vessel inner wall surfaces and others, various methodsare known in which the polymerization vessel inner wall surfaces,stirrers and so forth are coated with a polymer scale preventive agent(hereinafter “scale preventive agent”) by one-liquid coating to formcoating films (hereinafter “one-liquid coating method”). As the scalepreventive agent, usable are, e.g., a polar organic compound such as anamine compound, a quinone compound or an aldehyde compound or a dye orpigment (Japanese Patent Publications (kokoku) Nos. 45-30343 and45-30835), a polar organic compound or dye treated with a metal salt(Japanese Patent Publication (kokoku) No. 52-24953, a mixture of anelectron-donating compound and an electron-accepting compound (JapanesePatent Publication (kokoku) No. 53-28347), a condensation reactionproduct of 1-naphthol with formaldehyde (Japanese Pre-examination PatentPublication (kokai) No. 57-164107), a condensation reaction product of aphenol compound with formaldehyde (Japanese Pre-examination PatentPublication (kokai) No. 57-192413), a polyaromatic amine (JapanesePatent Publication (kokoku) No. 59-16561), a self-condensation productof a polyhydric phenol or a self-condensation product of a polyhydricnaphthol (Japanese Pre-examination Patent Publication (kokai) No.54-7487), a condensation reaction product of a ketone resin with aphenol compound (Japanese Pre-examination Patent Publication (kokai) No.62-236804), a condensation reaction product of an aromatic amine with anaromatic nitro compound and a material obtained by making the compoundbasic (Japanese Patent Publication (kokoku) No. 60-30681), and acondensation reaction product of an aromatic amine with a quinonecompound (Japanese Pre-examination Patent Publication (kokai) No.61-7309).

In the case of polymer scale preventive coating films obtained by suchone-liquid coating methods, scales tend to adhere to the vicinity of agas-liquid boundary surface in the polymerization vessel duringpolymerization, or, depending on the composition of a polymerizationreaction mixture, scales tend to adhere to the whole wall surface.Accordingly, to prevent this, it is known to mix in a coating liquidcontaining the scale preventive agent a water-soluble polymeric compoundsuch as an anionic polymeric compound, an amphoteric polymeric compound,a cationic polymeric compound or a hydroxyl-group-containing polymericcompound; an inorganic colloid; or a substance having no affinity formonomers, as exemplified by an inorganic salt such as an alkali metalsalt (hereinafter “scale preventive auxiliary agent”). These one-liquidcoating methods are effective for preventing the adhesion of polymerscales when monomers having ethylenic double bonds are polymerized inpolymerization vessels.

In the one-liquid coating method of coating the scale preventive agentby spray coating, the coating film is formed by a process comprising thefollowing steps 1 to 3. Step 1: A coating liquid containing the scalepreventive agent is coated on the polymerization vessel inner wallsurface and other surfaces with which monomers come into contact. Step2: The coated surfaces are dried to form a dry film. Step 3: The surfaceof the coating film thus formed is washed to remove any excess coatingliquid.

When the above spray coating is used, the surfaces of baffles andstirring blades that face polymerization vessel inner wall surfacesstand within the dead angle from a spray nozzle. Since it is hard forthe coating liquid to reach the surfaces of such portions standing blindor hidden from the spray nozzle, the scale preventive agent can not becoated thereon in the same way as on the surfaces not standing blind.Thus, it is difficult to form a uniform coating film over the surfacesstanding blind and the surfaces not standing blind. If a coating film ina quantity effective enough to prevent the adhesion of polymer scales isintended to be formed also on the blind surfaces, it is inevitable touse a coating liquid containing the scale preventive agent in a largerquantity than that for the other surfaces. It follows that anunnecessarily excess preventive agent is applied on the surfaces notstanding blind. Hence, the coating film thus formed have had an unevencoating thickness and the coating film have had a larger thicknesslocally than is necessary.

The formation of polymer scale preventive coating films by spray coatinghas also had the following problems.

(1) Usually, the coating film comprising the scale preventive agent isformed previously for each polymerization batching. Since it is commonfor the scale preventive agent to have a color, the scale preventiveagent is repeatedly coated as the polymerization is batched repeatedlyin a larger number, so that the coating film may have a large thicknessat some part. The part having such a thick coating film may come off tobecome included into the reaction mixture, or the scale preventive agentmay be coated on polymer scales having already adhered to thepolymerization vessel inner wall surfaces and others and may come offtogether with a part of the scales to mix into the resultantpolymerization products. This may cause colored particles or fish eyesbrought in their formed products or may cause a low product quality suchas a high initial discoloring of formed products, disadvantageously.

(2) As stated above, the effect of preventing scales at the surfacesstanding blind or hidden in the polymerization vessel, standing withinthe dead angle from the spray nozzle, can not be said to be so muchsufficient, considering the scale preventive agent applied in a fairlylarger quantity than that on other surfaces.

(3) The spray coating requires a drying step of drying the coatedsurfaces, and takes a time necessary for forming the coating film of thescale preventive agent. Accordingly, in respect of an improvement ofproductivity, it is sought to shorten the time necessary for forming thecoating film.

As a measure for eliminating the above disadvantages in the spraycoating, a method is proposed in which a coating liquid containing ascale preventive agent is coated using steam as a carrier (hereinafter“steam coating”) (Japanese Patent Publication (kokoku) No. 1-5044). Asthe coating liquid in this method, used is a coating liquid comprised ofthe scale preventive agent alone or a coating liquid to which the scalepreventive auxiliary agent is further added.

This steam coating has the following advantages.

(1) A thin and uniform coating film of the scale preventive agent,necessary for preventing the adhesion of scales effectively can beformed using the coating liquid in a small quantity.

(2) The coating film of the scale preventive agent, necessary forachieving the scale prevention effect can be formed using the coatingliquid in a small quantity, also on the portions standing blind orhidden in the polymerization vessel, standing within the dead angle fromthe spray nozzle. Thus, the polymer scale prevention effect can beattained also on these portions.

(3) The drying step is unnecessary in the coating film forming step, sothat the time necessary for forming the coating film of the scalepreventive agent can be shortened.

Incidentally, in the steam coating, the coating liquid and steam aremixed so that the coating liquid is carried by the steam and can beapplied to the polymerization vessel inner wall surfaces and others.Accordingly, the concentration of the scale preventive agent in thecoating liquid is set taking account of the fact that the solution isdiluted with steam. Usually, the concentration of the scale preventiveagent in the coating liquid for steam coating is set 4 to 40 times thatof the one for spray coating, although the amount of a scale preventiveagent necessary in steam coating is approximately equivalent to thatnecessary in spray coating.

In contrast to the advantages, the steam coating has problems on thefollowing points.

(1) Although the steam coating enables uniform coating in apolymerization vessel, the deposition of scale can be preventedinsufficiently around the interface between the gas-liquid phases.

(2) As the result of the insufficient prevention of scale depositionaround the interface between gas-liquid phases, the polymer scaledeposition will grow around the interface with repetition ofpolymerization runs. A part of the grown deposited scale may peel offthe inner surfaces of the polymerization vessel during polymerizationand be incorporated into a polymer product to cause formation offisheyes.

(3) A scale preventive agent is coated on the inner surfaces of apolymerization vessel repeatedly as polymerization runs are repeated.Consequently, the layer of the scale preventive agent become thickergradually. A part of the thick layer of the agent may peel off duringpolymerization and be incorporated into polymer products to causecolored particles. The colored particles will lower anti-initialdiscoloration properties, particularly luminosity index L, of polymerproducts.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a process for producinga polymer by polymerizing a monomer having an ethylenic double bond,which can shorten the time for forming coating films of scale preventiveagents to improve productivity, can improve the effect of preventingscales, can make colored particles less mix into polymer productsobtained by this process, can lessen fish eyes and initial discoloringof formed products and can improve the quality of polymeric products andtheir formed or molded products.

Accordingly, as a means for achieving the above object, the presentinvention provides a process for producing a polymer by polymerizing ina polymerization vessel a monomer having an ethylenic double bond,wherein

the polymerization vessel has a polymer scale preventive coating film onits inner wall surfaces and other surfaces with which the monomer comesinto contact during polymerization;

the coating film being formed by coating a coating liquid containing:

(A) a compound selected from the group consisting of an aromaticcompound having 5 or more conjugated π bonds and a heterocyclic compoundhaving 5 or more conjugated π bonds; and

(B) at least one compound selected from the group consisting of aninorganic colloid, a chelate reagent, a metal compound that produces ametal ion capable of forming a complex having at least two coordinationnumbers, and an acid;

the coating liquid being coated by means of steam as a carrier.

According to the polymerization process of the present invention, thetime for forming coating films of scale preventive agents can beshortened to improve productivity, and also, when monomers having anethylenic double bond are polymerized, polymer scales can be preventedeffectively from adhering to not only wall surfaces at the liquid-phaseportion in the polymerization vessel but also stirrers, baffle surfacesfacing the wall surface, and the vicinity of the boundary surfacebetween the gaseous phase and the liquid phase. Hence, the quality ofpolymer products can be improved and the colored particles can be madevery less mix into polymers, and also formed products obtained byforming the polymers into sheets can be made to have very less fish eyesand also have good anti-initial discoloring.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings,

FIG. 1 schematically illustrates the arrangement in a polymerizationapparatus; and

FIG. 2 schematically illustrates the arrangement in anotherpolymerization apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be described below in detail. In thefollowing, the polymer scale preventive agent is called “scalepreventive agent”.

[Component (A)]

The aromatic compound and heterocyclic compound used in the firstcoating liquid each have 5 or more conjugated π bonds. In the presentspecification, the term “π bonds” is meant to be double bonds and triplebonds, including, e.g., C═C, C≡C, N═N, C═N, C═S and C═O, and the term“conjugated π bonds” is meant to be a series of π bonds wherein eachpair of adjacent π bonds are connected to each other through a singlebond and all of the πbonds have a mutually conjugated relationship witheach other. The aromatic compound having 5 or more conjugated π bondsand the hetero cyclic compound having 5 or more conjugated π bonds areherein called together generically as “conjugated π bond compound” insome cases. The 5 or more π bonds are present in the conjugated πbondcompound may form a single conjugation group or two or more conjugationgroups.

Aromatic compound having 5 or more conjugated π bonds:

The aromatic compound having 5 or more conjugated π bonds may includebenzene derivatives, naphthalene derivatives, polynuclear aromaticcompounds, quinones, non-benzene type aromatic compounds, and aromaticcompound condensation products having a weight-average molecular weight,which term herein means weight-average molecular weight in terms ofpolystyrene as measured by gel permeation chromatography, of 500 ormore.

First, as benzene derivatives, there may be included:

phenols and derivatives thereof, such as 3,7-dihydroxy-10-methylxantheneand hydroxyanthraquinone;

aromatic amines and derivatives thereof, such as quinoline, carbazole,o-phenanthroline, p-phenanthroline, 3,6-diaminoacridine,3-aminophenothiazine, 2-aminophenazine, phenothiazine,2-hydroxy4-methylquinoline;

nitro and nitroso derivatives, such as phenazine, phenazine oxide,1-phenylazo-2-naphthol, triphenyldioxadine and 4-nitroxanthone;

aromatic aldehydes such as benzoflavin;

benzene derivatives having further one substituent other than aldehydegroup, such as 1-hydroxy-2,4-methylfluorone, 3-phenylcoumarone, ethylcoumarine-3-carboxylate, 3-acetylcoumarine,5-chloro-3-(4-hydroxyphenyl)anthranyl and 3-nitroacridone;

benzene derivatives having further one substituent other than acylgroup, such as xanthone, 2-benzoylxanthone, xanthene and fluorene;

benzene derivatives and toluene derivatives having three or moredifferent substituents, such as7-acetoxy-8-methoxy-3-(2-nitrophenyl)carbostyryl;

aralkyl compounds, such as 9-benzylacridine; and diazo compounds and azocompounds, such as 1,1′-azonaphthalene and azoxyphenol.

Next, as naphthalene derivatives, there may be included:

alkyl, alkenyl and phenylnaphthalenes, such as 2-methylnaphthalene,1-ethyl-naphthalene, 2-ethylnaphthalene and 1,2-dimethylnaphthalene;

dinaphthyls, such as 1,1′-dinaphthyl, 1,2′-dinaphthyl and2,2′-dinaphthyl;

naphthylarylmethanes, such as 1-benzylnaphthalene, 2-benzylnaphthalene,1-(α,α-dichlorobenzyl)naphthalene, diphenyl-α-naphthyl-methane,diphenyl-β-naphthylmethane and di-α-naphthylmethane;

naphthylarylethanes, such as 1,2-di-α- naphthylethane and1,2-di-β-naphthylethane;

hydronaphthalenes such as 1,2-dihydronaphthalenes,1,4-dihydronaphthalene and 1,2,3,4-tetrahydronaphthalene;

nitronaphthalenes and derivatives thereof, such asnitromethyl-naphthalene, nitroalkylnaphthalene, nitrophenyl-naphthalene,halo-nitronaphthalene, halo-dinitro-naphthalene, nitrosonaphthalene,diaminonaphthalene, triaminonaphthalene and tetraaminonaphthalene;

halogenated naphthalenes, such as 1-fluoro-naphthalene,1-chloronaphthalene and 1-chloro-3,4-dihydronaphthalene;

naphthylhydroxylamines, naphthylpyrazines and naphthylureas, such asα-naphthylhydroxylamine, β-naphthylthiohydroxyl-amine,N-nitroso-α-naphthylhydroxylamine, α-naphthylhydrazine and1,2-dibenzocarbazole;

naphthalene-based aralkyl compounds, such as dibenzoanthracene,acenaphthene, diphenylnaphthylchloromethane and nitromethylnaphthalene;

naphthoaldehydes and derivatives thereof, such as α-naphthoaldehyde and2-(2,4-dinitrophenyl)-1-(α-naphthyl)-ethylene;

acetonaphthenes and benzoylnaphthalenes, such as1,2;5,6-dibenzanthracene, 2′-methyl-2,1 ′-dinaphthyl ketone,2-methyl-1,1′-dinaphthyl ketone and styryl-2-naphthyl ketone.

As the polynuclear aromatic compounds, there may be included:

anthracenes and derivatives thereof, such as anthracene,1,2-dihydroanthracene, 1-chloroanthracene, 1,4-dichloroanthracene,1-nitroanthracene, 9,10-dinitroanthracene, 1-aminoanthracene,2-dimethylaminoanthracene, 2-anilinoanthracene, 9-methylaminoanthracene,1,4-diaminoanthracene;

phenanthrenes and derivatives thereof, such as phenanthrene,9,10-dihydrophenanthrene, 1,2,3,4-tetrahydrophenanthrene and1-chlorophenanthrene;

phenanthrenequinones, such as phenanthrene-1,2-quinone andphenanthrene-1,4-quinone; and

polynuclear aromatic compounds and derivatives thereof, such aspentacene, hexacene, benzophenanthrene, benzo[a]anthracene, pyrene andcoronene.

As quinones and derivatives thereof, there may be included:

naphthoquinones and derivatives thereof, such as 1,2-naphthoquinone,3-hydroxy-2,2′-binaphthyl-1,4;3′,4′-diquinone, 5,6-benzoquinoxaline,1,2-benzophenazine, 2-benzoazo-1-naphthol,4-(2,4-dihydroxyphenyl)-1,2-dihydroxynaphthalene,4-(3,4,5-trihydroxyphenyl)-1,2-dihydroxynaphthalene and 1,4-naphthol;and

anthraquinones and derivatives thereof, such as 1,2-anthraquinone,2,3-anthraquinone, 1,4-anthraquinone, alizarin, quinizarin, chrysazin,hystazarin, anthraflavin, isoanthraflavin, anthragallol, purpurin,hydroxyanthrarufin, hydroxychrysazin, hydroxyflavopurpurin, quinazarinand alizarinpentacyanine.

Further, as the non-benzene aromatic compounds, there may be included,for example, azulene, cyclodecapentane, clotetradecaheptane,cyclooctadecanonaene, clotetracosadodecaene, heptalene, fulvalene,sesquiflulvalene, heptafluvalene and perinaphthene.

The aromatic compound condensation products having a molecular weight of500 or more may suitably be aromatic compound condensation productshaving preferably a eight-average molecular weight of from 500 to70,000, and ore preferably from 1,500 to 30,000.

Preferred aromatic compound condensation products include the compoundsbelow, for instance.

Aldehyde compound/aromatic hydroxyl compound condensation products

The aldehyde compound/aromatic hydroxyl compound condensation product isa condensation product of an aldehyde compound with an aromatic hydroxylcompound. The use of such aldehyde compound/aromatic hydroxyl compoundcondensation products in scale preventive agents are disclosed in, forexample, Japanese Pre-examination Patent Publication (kokai) No.57-192413, Japanese Patent Publication (kokoku) No. 6-62709, JapanesePre-examination Patent Publication (kokai) No. 57-164107 and WO98/24820

The aldehyde compounds include, for example, formaldehyde, acetaldehyde,propionaldehyde, butylaldehyde, acrolein, crotonaldehyde, benzaldehyde,furfural, phenylacetaldehyde, 3-phenylpropionaldehyde and2-phenylpropionaldehyde. From industrial and economical viewpoints,formaldehyde and acetaldehyde are advantageous.

The aromatic hydroxyl compounds include, for example, dihydroxybiphenylcompounds, naphthol compounds, phenol compounds, tannins and dimericcompounds of 2,3-dihydroxynaphthalene.

Examples of the dihydroxybiphenyl compounds include2,2′-dihydroxybiphenyl, 2,2′-dihydroxy-5,5′-dimethylbiphenyl,2,2′-dihydroxy-4,4′,5,5′-tetramethylbiphenyl,2,2′-dihydroxy-5,5′-dichlorobiphenyl,2,2′-dihydroxy-5,5′-dichlorohexylbiphenyl and2,2′-dihydroxy-5,5′-di-tert-butylbiphenyl. In particular, from anindustrial viewpoint, 2,2′-dihydroxybiphenyl is preferred.

Examples of the naphthol compounds include 1-naphthol, 2-naphthol,1,3-dihydroxynaphthalene, 1,5-dihydroxynaphthalene,1,7-dihydroxynaphthalene, 6-hydroxy-2-naphthoic acid,2-hydroxy-1-naphthoic acid, 1-hydroxy-2-naphthoic acid and1-hydroxy-8-naphthoic acid.

Examples of the phenol compounds include phenol, cresol, pyrogallol,hydroxyhydroquinone, resorcin, catechol, hydroquinone, bisphenol-A,hydroxybenzoic acid, dihydroxybenzoic acid, 2-hydroxy-5-methoxybenzoicacid and salicylic acid.

Examples of the tannins include tannic acid, Chinese gallotannin,Turkish gallotannin, sumac tannin, quebracho tannin, and tannin ofpersimmon (shibuol).

The dimeric compounds of 2,3-dihydroxynaphthalene include, for example,2,3,2′,3′-tetrahydroxybinaphthyl.

The above condensation product of an aldehyde compound with an aromatichydroxyl compound can be produced by reacting these reactive componentsin a suitable medium in the presence of a catalyst, usually at roomtemperature to 200° C. for 2 to 100 hours, preferably at 30 to 150° C.for 3 to 30 hours. Each of the aromatic hydroxyl compound and thealdehyde compound can be used singly or in combination of two or morekinds.

The medium in which the above condensation reaction is carried outincludes, for example, water; and organic solvents, such as alcohols,ketones and esters. The organic solvents include, for example, alcohols,such as methanol, ethanol and propanol; ketones, such as acetone andmethyl ethyl ketone; and esters, such as methyl acetate and ethylacetate.

The medium in which the above condensation reaction is carried out has apH in the range of usually from 1 to 13, and pH adjusters may be usedwithout any particular limitations.

The catalyst used in the above condensation reaction includes, forexample, acidic catalysts, such as sulfuric acid, hydrochloric acid,perchloric acid, p-toluenesulfonic acid, methanesulfonic acid andtrifluoromethanesulfonic acid; and basic catalysts, such as NaOH, KOHand NH₄OH.

The ratio of the aldehyde to the aromatic hydroxyl compound used whenthe condensation reaction is carried out depends on the types of thealdehyde compound, aromatic hydroxyl compound, solvent and catalystused, the reaction time, the reaction temperature and so forth.Generally, it is preferable to use from 0.1 to 10 mols of the aldehydecompound per mol of the aromatic hydroxyl compound.

Pyrogallol/acetone condensation products

The pyrogallol/acetone condensation product is a condensation product ofpyrogallol with acetone, the molar ratio of the pyrogallol to theacetone being in the range of usually from 1/0.1 to 1/10, and themelting point thereof being usually from 100 to 500° C. The meltingpoint increases with an increase in molecular weights. For example,melting points of from 160 to 170° C. correspond to molecular weights offrom 1,450 to 1,650; and melting points of from 200 to 220° C., tomolecular weights of from 2,600 to 4,000. The use of suchpyrogallol/acetone condensation products in scale preventive agents isdisclosed in, for example, Japanese Pre-examination Patent Publication(kokai) No. 4-328104.

The pyrogallol/acetone condensation product can be produced bydissolving pyrogallol in acetone, and condensing them in the presence ofa condensation catalyst. The pyrogallol is used in an amount of usuallyfrom 1 to 100 parts by weight per 100 parts by weight of the acetone. Asthe condensation catalyst, for example, phosphorus oxychloride is used.The reaction may be carried out at room temperature to 100° C.

Polyhydric phenol self-condensation products and polyhydric naphtholself-condensation products

Polyhydric phenols are exemplified by catechol, resorcinol,chlororesorcinol, hydroquinone, phloroglucinol and pyrogallol;dihydroxytoluene and dihydroxyxylene; trihydroxytoluene andtrihydroxyxylene; ethyl-, propyl-, butyl- or pentyl-di- ortri-hydroxybenzene; and rihydroxybenzene. Polyhydric naphthols areexemplified by naphthol derivatives, such as 1,3-, 1,4-, 1,5- or1,7-dihydroxynaphthalene. The use of such polyhydric phenolself-condensation products and polyhydric naphthol self-condensationproducts in scale preventive agents is disclosed in, for example,Japanese Pre-examination Patent Publication (kokai) No. 54-7487.

The polyhydric phenol self-condensation product or polyhydric naphtholself-condensation product can be produced by heating polyhydric phenolor polyhydric naphthol in an inert atmosphere, such as nitrogen, argonor the like, at a temperature ranging from 200 to 350° C. for 4 to 100hours. In this reaction, various catalysts may be used, as exemplifiedby zinc chloride, aluminum chloride and sodium hydroxide.

Ouinone compound condensation products

The quinone compound condensation products include, for example, (A) aself-condensation product of a quinone compound, and (B) a condensationproduct of a quinone compound with at least one compound selected fromthe group consisting of an aromatic hydroxyl compound and an aromaticamine compound. The use of such quinone compound condensation productsin scale preventive agents is disclosed in, for example, JapanesePre-examination Patent Publication (kokai) Nos. 5-112603 and 6-56911.

The quinone compounds include, for example, benzoquinones andderivatives thereof, such as o-, m- or p-benzoquinone, tolu-p-quinone,o-xylo-p-quinone, thymoquinone, 2-methoxybenzoquinone, gentisyl quinone,polyporic acid and ubiquinone-n; naphthoquinones and derivativesthereof, such as 6-methyl-1,4-naphthoquinone,2-methyl-1,4-naphthoquinone, α-naphthoquinone, juglone, lawsone,plumbagin, alkannin, echinochrome A, vitamin k₁, vitamin k₂, shikonin,β,β′-dimethyl acrylshikonin, β-hydroxyisovaleroshikonin andteracrylshikonin; anthraquinones and derivatives thereof, such astectoquinone, 3-hydroxy-2-methylanthraquinone, anthraquinone,2-hydroxyanthraquinone, alizarin, xanthopurpurin, rubiadin, munjistin,crysophanic acid, carminic acid, kermesic acid and laccaic acid A; andphenanthrenequinones such as phenanthrenequinone.

The aromatic amine compounds are specifically exemplified by aniline,o-, m- or p-phenylene-diamine, o-, m- or p-chloroaniline, o-, m- orp-methylaniline, N,N-dimethyl-p-phenylenediamine,4-chloro-o-phenylenediamine, 4-methoxy-o-phenylenediamine,2-amino-4-chlorophenol, 2,3-diaminotoluene, 4-amino-2-aminophenol, o-,m- or p-aminophenol, o-, m-or p-aminobenzoic acid, 2,3-, 2,4-, 2,5-,2,6-, 3,4-, 3,5- or 4,6-diaminobenzoic acid, 3- or 4-aminophthalic acid,2-, 4- or 5-aminoisophthalic acid, 5 4,6-diaminoisophthalic acid, 2,5-or 2,6-diaminoterephthalic acid, 3-, 4- or 5-aminosalicylic acid,4-hydroxyanthranilic acid, o-, m- or p-aminobenzenesulfonic acid, 2,3-,2,4-, 2,5-, 2,6-, 3,4- or 3,5-diaminobenzenesulfonic acid,2-amino-1-phenol-4-sulfonic acid and6-amino-4-chloro-1-phenol-2-sulfonic acid, α-naphthylamine,β-naphthylamine, 1,5-diaminonaphthalene, 1-amino-5-hydroxynaphthalene,1,8-diaminonaphthalene, 2,3-diminonaphthalene, 4-amino-1-naphthol,1-amino-5-naphthol, 1,2-naphthylenediamine-7-carboxylic acid,1,5-naphthylenediamine-2-carboxylic acid,1,5-naphthylenediamine-4-carboxylic acid,1,6-naphthylenediamine-4-carboxylic acid,1,8-naphthylenediamine-4-carboxylic acid,1,2-naphthylenediamine-3-sulfonic acid,1,2-naphthylenediamine-4-sulfonic acid,1,2-naphthylenediamine-5-sulfonic acid,1,2-naphthylenediamine-6-sulfonic acid,1,2-naphthylenediamine-7-sulfonic acid,1,3-naphthylenediamine-5-sulfonic acid,1,3-naphthylenediamine-6-sulfonic acid,1,4-naphthylenediamine-2-sulfonic acid,1,4-naphthylenediamine-7-sulfonic acid,1,5-naphthylenediamine-2-sulfonic acid,1,5-naphthylenediamine-4-sulfonic acid,1,5-naphthylenediamine-7-sulfonic acid,1,6-naphthylenediamine-2-sulfonic acid,1,6-naphthylenediamine-4-sulfonic acid,1,6-naphthylenediamine-7-sulfonic acid,1,8-naphthylenediamine-4-sulfonic acid,1,8-naphthylenediamine-3,6-disulfonic acid,1,8-naphthylenediamine-4,5-disulfonic acid,α-amino-β-naphthalenepropionic acid, α-amino-β-naphthalenecarboxylicacid, 2-naphthylamine-1-sulfonic acid, 8-naphthylamine-1-sulfonic acid,5-naphthylamine-1-sulfonic acid, 1-amino-2-naphthol-4-sulfonic acid,2-amino-8-naphthol-6-sulfonic acid (γ-acid),2-amino-5-naphthol-7-sulfonic acid (J-acid) and1-amino-8-naphthol-3,6-disulfonic acid (H-acid), and diphenylamines,such as 4-aminodiphenylamine, 2-aminodiphenylamine,4,4′-diaminodiphenylamine, 4-hydroxydiphenylamine,4-amino-3′-methoxydiphenylamine, 4-amino-4′-hydroxydiphenylamine,4-carboxydiphenylamine, 4-amino-4′-carboxydiphenylamine,4-sulfodiphenylamine and 4-amino-4′-sulfodiphenylamine.

The aromatic hydroxyl compounds are exemplified by phenols andderivatives thereof, such as phenol, hydroquinone, resorcinol, catechol,hydroxyhydroquinone, pyrogallol, o-, m- or p-chlorophenol, o-, m- orp-hydroxybenzoic acid, 2,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoicacid, 2,6-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid,3,5-dihydroxybenzoic acid and 2,5-, 2,6- or 3,5-dihydroxytoluene.

In addition, they are exemplified by naphthols and derivatives thereof,such as α-naphthol, β-naphthol, 1,3-, 1,4-, 1,5-, 2,3-, 2,6- or2,7-dihydroxynaphthalene, 1-hydroxy-2-naphthoic acid and3-hydroxy-2-naphthoic acid.

The self-condensation of a quinone compound or the condensation of aquinone compound with an aromatic hydroxyl compound and/or an aromaticamine compound is carried out in an organic solvent medium, optionallyin the presence of a condensation catalyst. The organic solvent mediumhas a pH within the range of from 1 to 13, preferably from 4 to 10, andpH adjusters may be used without any particular limitations. The pHadjusters used include acidic compounds, for example, phosphoric acid,sulfuric acid, phytic acid and acetic acid; and alkali compounds, forexample, alkaline metal compounds or ammonium compounds, such as LiOH,KOH, NaOH, Na₂CO₃, Na₂SiO₃, Na₂HPO₄ and NH₄OH; and organic aminecompounds, such as ethylenediamine, monoethanolamine andtriethanolamine.

As the medium for the condensation reaction, organic solvents asexemplified by alcohols, ketones and esters, or mixed solvents of waterand organic solvents miscible with water are preferred. Usable organicsolvents miscible with water include, for example, alcohols, such asmethanol, ethanol and propanol; ketones, such as acetone and methylethyl ketone; and esters, such as methyl acetate and ethyl acetate.

The condensation catalyst may be optionally used which is exemplified byazo catalysts such as α,α′-azobisisobutylonitrile andα,α′-azobis-2,4-dimethylvaleronitrile; elementary or molecular singlehalogens, such as iodine, bromine and chlorine; peroxides, such ashydrogen peroxide, sodium peroxide, benzoyl peroxide, potassiumpersulfate, ammonium persulfate, peracetic acid, cumene hydroperoxide,perbenzoic acid and p-menthane hydroperoxide; oxygen acids or oxygenacid salts, such as iodic acid, periodic acid, potassium periodate andsodium perchlorate. Incidentally, since the quinone compound acts as acondensation catalyst, the condensation reaction takes place even in theabsence of a condensation catalyst.

The condensation reaction may be generally carried out at roomtemperature to 200° C. for 0.5 to 100 hours.

When (a) a quinone compound and (b) an aromatic hydroxyl compound and/oran aromatic amine compound are condensed, the proportion of bothreactive components used depends on the types of the aromatic aminecompounds, quinone compounds and aromatic hydroxyl compounds, thereaction temperature and the reaction time. It is preferable to use from0.01 to 10.0 mols of the component (b) per mol of the component (a).

Sulfide Compounds of Aromatic Hydroxyl Compounds

Sulfide compounds of aromatic hydroxyl compounds refer to condensationproducts of aromatic hydroxyl compounds with sulfur chlorides such assulfur monochloride and sulfur dichloride. Use of such sulfide compoundsof aromatic hydroxyl compounds in the scale preventive agent isdisclosed in, e.g., Japanese Pre-examination Patent Publication (kokai)Nos. 4-311702, 4-339801, 5-155905 and 6-9711.

The aromatic hydroxyl compounds may include aromatic hydroxyl compoundsof naphthol compounds described above, phenol compounds and the like.

To obtain the sulfide compounds, various methods are available. Forexample, a method is available in which the above phenols and sulfurchlorides such as sulfur monochloride and sulfur dichloride aresubjected to condensation reaction. This reaction is carried out in anorganic solvent inert to sulfur chlorides, in which a polyhydric phenolhas been dissolved. Such an organic solvent may include, e.g., aromatichydrocarbons such as toluene, xylene and chlorobenzene, and ethylenedichloride, chloroform and ethyl acetate. The phenol and the sulfurchloride may be in such a ratio that the latter is from about 0.5 to 2mols, and preferably from about 0.9 to 1.2 mols, per mole of the former.The reaction may be carried out at a temperature of from about 50° C. toabout 150° C. Hydrogen chloride formed as a by-product may bevolatilized, or, in a closed system, a dehydrochlorinating agent such astriethylene-amine may be used. After the reaction has been completed, inan instance where the reaction product stand dissolved in the solvent,the solvent may be removed by evaporation to take out the reactionproduct. In an instance where the reaction product stand deposited,solid-liquid separating operation such as filtration may be carried outto take out the reaction product.

As another method for obtaining the sulfide compound, a method isavailable in which a polyhydric phenol and a small amount of an alkalihydroxide are heated and melted, sulfur powder is added thereto littleby little and further the temperature is raised to about 150° C. toabout 200° C., where the reaction is carried out while releasing to theoutside of the system the hydrogen sulfide being formed, the reactionmixture is cooled and thereafter dissolved in the solvent describedlater, followed by filtration to collect the insoluble matter, which isthen neutralized with a dilute acid, and the aqueous phase is removed toobtain the compound in the form of a solution.

Heterocyclic compound having 5 or more conjugated π bonds:

The heterocyclic compounds having 5 or more conjugated πbonds include,for example, oxygen-containing heterocyclic compounds,nitrogen-containing heterocyclic compounds, sulfur-containingheterocyclic compounds, dicyclic compounds having a nitrogen atompossessed in common by the two rings, and alkaroids.

First, as the oxygen-containing heterocyclic compounds, there may beincluded:

benzofuran, isobenzofuran, dibenzofuran and derivatives thereof, such asfurano-[2′,3′-7,8]flavone, 9-phenylanthracene,o-hydroxymethyltriphenylcarbinol, 3,3′-diphenylphthalide, rubrene,α-sorinine and phenazone;

pyran derivatives and pyrone derivatives, such as2-p-hydroxyphenyl-4,6-diphenylpyrylium ferrichloride, anhydrobase,benzopyran and 6-phenylcoumarin;

chromenol derivatives and chromene derivatives, such as6-methyl-2,3-diphenylchromone,6-methyl-2,3-diphenyl-4-(p-tolyl)-1,4-benzopyran-4-ol, chromanol,γ-chromene, hydroxychmarone, chromene, cyanizine chloride, fisetin,chrysinidine, apigenidin and rotoflavinidine;

flavone, flavonol and isoflavon derivatives, such as flavonol, flavone,fukugetin;

coumarin, its derivatives, isocoumarin and its derivatives, such as7-hydroxy-3,4-benzocoumarin, dicoumarol, angelicin, psoralen, bergapten,bergaptol, xanthotoxin, xanthotoxal, isopimpinellin, pimpinellin,oroselol, oroselone, peucedanin, hydroxypeucedanin, ostruthol,medakenine, nodakenetin, seselin, xanthyletin, xanthoxyletin; and

xanthone and related compounds; such as dixanthylene, 9-phenylxanthene,isoxanthone, 1,2,7,8-dibenzoxanthene, 3,9-diphenylxanthene,9,9-diphenylxanthene, and the like.

Next, the nitrogen-containing heterocyclic compounds may include:

indoles, such as indolo[3,2-c]quinoline, indolo[1,2-c]quinazoline,2-(1-naphthyl)-3-triphenylmethylindole,2-(2-naphthyl)-3-triphenylmethylindole, 3,3′-diindolyl and3,2′-diindolyl;

oxoderivatives of indole, such as 3-(4-ethoxy-1-naphthyl)hydroxyindoleand indophenine;

carbazoles, such as 1-phenyl-1,2,3-benzotriazole, 2,2′-diaminodiphenyl,1,1′-dicarbazole;

porphyrins, such as porphyrazine, magnesium octamethyltetraazaporphyrin,azadipyromethine, diazacoproporphyrin, porphine andmesotetraphenylporphyrin;

oxazoles, such as phenanthrooxazole;

thiazoles, such as α-naphthothiazole, β-naphthothiazole,naphtho[1,2]thiazole, 2-methyl[1,2]thiazole,2-phenylnaphtho[1,2]thiazole, 2-methylnaphtho[2,1]-thiazole,2-hydroxynaphtho[2,1]thiazole, 2-aminonaphtho[1,2]thiazole and2-mercaptonaphtho[1,2]-thiazole;

oxadiazoles, such as naphtho[1,2]furazane;

quinoline and related compounds, such as quinoline, quinaldine,quinaldine-N-oxide, ethylquinoline, 2-phenylquinoline,3-methylquinoline, 4-phenylquinoline, 6-methylquinoline and2,4-dimethylquinoline;

isoquinoline and related compounds, such as 1-methylisoquinoline,1-phenylisoquinoline, 4-phenylisoquinoline, 1,1′-biisoquinoline and5,5′-biisoquinoline;

acridine and related compounds, such as acridine, 1-methylacridine,9-phenylacridine, 9-(3-pyridinyl)acridine, 2-acridinol,acridine-3,6-diol, 4-methoxyacridine, 9-phenoxyacridine,1-nitroacridine, 4-aminoacridine, 1-aminoacridine,9-phenylaminoacridine, 9-acridine and 3,6-diamino-4,5-dimethylacridine;

phenanthridines, such as 3,4-benzoquinoline, 6-methylphenanthridine,6-aminomethylphenanthridine and 6-phenylphenanthridine;

anthrazolines, such as pyrido[2,3-g]quinoline,2,7-diphenyl[2,3-g]quinoline, 2,8-diphenylpyrido[3,2-g]-quinoline;

phenanthroline and related compounds, such as 1,7-phenanthroline and1,10-phenanthroline;

pyridoindoles, such as 1,9-pyridoindole, 2,9-pyridoindole and4,9-pyridoindole;

naphthylidine and related compounds, such as 1,5-naphthylidine,1,7-naphthylidine, 1,8-naphthylidine, 3-amino-1,5-naphthylidine,2-amino-1,5-naphthylidine and 2-hydroxy-1,7-naphthylidine;

oxazine and related compounds such as phenoxazinone and resazurin;

thiazine and related compounds, such as phenothiazine,nitrophenothiazine, 4-amino-4′-anilinodiphenyl disulfide,2-chloro-10-(3-dimethylaminopropyl)phenothiazine,10-[1-methyl-3-piperidylmethyl)phenothiazine and2-acetyl-10-(3-dimethylaminopropyl)phenothiazine;

pyridazine and related compounds, such as cinnoline, 3-methylcinnoline,4-chlorocinnoline, 3-bromocinnoline, 4-cinnolinol, 4-aminocinnoline,phthalazine, 4-ethyl-2-phenylphthalazinone and phthalazine thiol;

pyrimidine and related compounds, such as sulfadiazine, sulfisomidine,pteridine, 2,4-pterine diol, 2-amino-6-methyl-4-pteridinol,xanthopterine, quinazoline, 2,4-dichloroquinazoline and2,3-diphenyl-4-quinazoline;

pyrazine related compounds, such as quinoxaline and 2-methylquinoxaline;

tri- and tetra-hetero six-membered cyclic compounds, such as1,2,4-benzotriazine and 1,2,4-benzotriazine-3-ol;

Further, the sulfur-containing heterocyclic compounds may include:

fused thiophene compounds, such as dihydronaphtho[2,1-b]-thianaphthene,1,3-diphenylisothianaphthene and dibenzothiophene;

five-membered monocyclic compounds containing 2 hetero atoms, such as3,4-dihydronaphtho-2,1-trithione, thiaflavone, thiacoumarin,thiaxanthene, thiaxanthohydrol, thiaxanthone, Milacil D, andbisthiaxanthylene;

six-membered cyclic compound having two or more hetero atoms, such asthianthrene, 2,7-dimethylthianthrene, 1-thianthrenyl lithium,1-chlorothianthrene and phenoxathine.

Further, other useful compounds may include:

dicyclic compounds having a nitrogen atom possessed in common by the tworings, such as 2:3-benzopyrrocoline,1,5,8-trimethyl-2:3-benzopyrrocoline and1-ethyl-5,8-dimethyl-2:3-benzopyrrocoline; and

alkaroids, such as casimiroin, 2-penthylquinoline,4-hydroxy-2-pentylquinoline and 4-methoxy-2-pentylquinoline.

Of the conjugated π bond compounds, it is preferable to use those whichare condensation products of aromatic compounds and have aweight-average molecular weight of 500 or more.

Of the condensation products of aromatic compounds, aldehydecompound/aromatic hydroxyl compound condensation products and quinonecompound condensation products are particularly preferred.

[Component (B)]

The component (B) used in the coating liquid will be described below.The component (B) is at least one compound selected from the groupconsisting of an inorganic colloid, a chelate reagent, a metal compoundthat produces a metal ion capable of forming a complex having at leasttwo coordination numbers, and an acid. These compounds are describedbelow in order.

Inorganic colloid

The inorganic colloids include, for example, colloids of oxides orhydroxides of metals selected from aluminum, thorium, titanium,zirconium, antimony, tin, iron and so forth; colloids of tungstic acid,vanadium pentoxide, selenium, sulfur, silica, gold, silver and silveriodide. Among them, preferred are colloids of oxides or hydroxides ofmetals selected from aluminum, titanium, zirconium, tin and iron; andcolloidal silica. These inorganic colloids may be those obtained by anyproduction processes on which there are no particulate limitations. Forexample, particulate colloids produced by a dispersion process usingwater as a dispersion medium or an agglomeration process are available.The colloidal particles have a size of preferably 1 to 500 nm.

Chelate reagent

The chelate reagent may preferably include (a) compounds not having anyacidic coordination group, as exemplified by cationic chelate reagentshaving a coordination group such as an —NH₂ group (primary amines,amides and hydrazine), an ═NH group (secondary amines and hydrazine), an≡N group (tertiary amines), an —N═N— group (azo compounds andheterocyclic compounds), an —NO₂ group (nitro compounds), an —N═O group(nitroso compounds), a ═C═N group (Schiff bases and heterocycliccompounds), a ═C═NH group (aldehydes, ketoimines and enamines), an —S—group (thioethers), a ═C═S group (thioketones and thioamides), an ≡Sgroup (heterocyclic compounds), an —SCN group (thiocyanato andisothiocyanato), a ═C═O group (aldehydes, ketones and quinones), an -O-group (ethers), a —COOR group (esters), an -N═O group (nitrosocompounds), and an ≡N→O group (N-oxides); and (b) compounds having anacidic coordination group, as exemplified by anionic chelate reagentshaving a coordination group such as an —OH group (alcohols), a —COOHgroup (carboxylic acids), an —SO₂H group (sulfonic acids), an ═N—OHgroup (oximes), an —SH group (thiols), and a group represented by theformula:

(thiocarboxylic acids). These may specifically include the followingexamples.

Diethylenetriamine, triethylenetetramine, triaminotriethylamine,tetrakis(β-aminoester)ethylenediamine, N,N′-dimethylethylenediamine,N,N′-tetramethylethylenediamine, 1,3-diaminorpopane, 1,2-diaminorpopane,bipyridine, terpyridine, o-phenanthroline, thiourea,gluoxazalbis(methylimine), acetylacetone, thenoyltrifluoroacetone,purine, piperidine, histamine, imidazole, 2,2′-diquinolyl,4,7-diphenyl-1,10-phenanthroline, o-phenylenediamine,3,3′-diaminobenzidine, diphenylcarpazide, diphenylcarpazone,benzoylmethane, dithizone, diphenyl thiocarodiazone, isonicotinic acidhydrazide, N-dihydroxyethylglycine, iminodiacetic acid, nitrilotriaceticacid, N-hydroxyethyliminodiacetic acid, ethylenediaminetetraacetic acid,N,N′-ethylenediaminediacetic acid,N-hydroxyethylethylenediaminetriacetic acid,diethdylenetriaminepentaacetic acid, 1,2-cyclohexanediaminetetraaceticacid, trimethylenediaminetetraacetic acid, ethylenebis(β-aminoethylether)-N,N,N′,N′-tetraacetic acid, ethylenediaminetetrapropionicdiaceticacid, ethylenediaminedipropionic acid,β-aminoethylphosphonic-N,N-diacetic acid,aminomethylphosphonic-N,N′-diacetic acid, 2,3-dimethylmercaptopropanol,sodium diethyldithiocarbamate, 8-hydroxyquinoline, dimethylglyoxime,glycine, aspartic acid, N,N′-dihydroxyethylethylenediamine,triethanolamine, α-furyldioxime, 1,2-dimercaptopropanol,α-benzoineoxime, thiooxine, and 2-mercaptobenzothiazole.

Metal compound that produces metal ion capable of forming complex havingat least two coordination numbers

The metal compound that produces a metal ion capable of forming acomplex having at least two coordination numbers is exemplified by metalcompounds that produce metal ions having two coordination numbers suchas Cu(I), Ag(I), Hg(I) and Hg(II), metal ions having four coordinationnumbers such as Be(II), B(III), Zn(II), Cd(II), Hg(II), Al(III), Co(II),Ni(II), Cu(II), Ag(II), Au(III), Pd(II) and Pt(II), metal ions havingsix coordination numbers such as Ca(II), Sr(II), Ba(II), Ti(IV), V(III),V(IV), Cr(III), Mn(II), Mn(III), Fe(II), Fe(III), Co(II), Co(III),Ni(II), Pd(IV), Cd(II), Al(III), Sc(III), Y(III), Si(IV), Sn(II),Sn(IV), Pb(II), Pb(IV), Ru(III), Rh(III), Os(III), Ir(III) andlanthanoids, metal ions having eight coordination numbers such asZr(IV), Hf(IV), Mo(IV), W(IV), U(IV) and actinoids, as exemplified byhalides, nitrates, sulfates, hydroxides, oxides and organic acid salts(such as oxalates and acetates) of any of these metallic elements.

Acid

The acid may include inorganic acids such as phosphoric acid,pyrophosphoric acid and polyphosphoric acid; and organic acids such asterephthalic acid, 1,12-dodecanedicarboxylic acid, 1-dodecanedisulfonicacid, benzoic acid, lauric acid, sulfanilic acid, p-styrene sulfonicacid, propionic acid, salicylic acid, urocanic acid, L-asciorbic acid,D-isoasciorbic acid, chlorogenic acid, caffeic acid, p-toluenesulfonicacid, sorbic acid, β-naphthoquinone 4-sulfonic acid, phytic acid andtannic acid.

The above component (B) may more preferably be used in combination oftwo or more types. For example, preferred are use in combination of thechelate reagent with the metal compound that produces a metal ioncapable of forming a complex having at least two coordination numbersand use in combination of the chelate reagent with the acid.

[Coating Liquid]

The coating liquid is prepared by dissolving the above components (A)and (B) in a proper solvent. The solvent includes, for example, water;alcohol solvents, such as methanol, ethanol, propanol, butanol,2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, 3-methyl-1-butanol,2-methyl-2-butanol and 2-pentanol; ketone solvents, such as acetone,methyl ethyl ketone and methyl isobutyl ketone; ester solvents, such asmethyl formate, ethyl formate, methyl acetate, ethyl acetate and methylacetoacetate; ether solvents, such as 4-methyldioxolane and ethyleneglycol diethyl ether; furans; and non-protonic solvents, such asdimethylformamide, dimethyl sulfoxide, acetonitrile,N-methyl-2-pyyrolidone and 1,3-dimethyl-2-imidazolidinone. The solventsmay be appropriately used singly or as a mixed solvent of two or morethereof.

Among the above solvents, preferred are water and a mixed solvent ofwater and an organic solvent miscible with water. Among the aboveorganic solvents, organic solvents miscible with water include alcoholsolvents, such as methanol, ethanol and propanol; ketone solvents, suchas acetone and methyl ethyl ketone; ester solvents, such as methylacetate and ethyl acetate; and non-protonic solvents, such asN-methyl-2-pyyrolidone and 1,3-dimethyl-2-imidazolidinone. Particularly,it is preferred that alcohol solvents and non-protonic solvents areused. In the case where a mixed solvent of water and an organic solventmiscible with water is used, the organic solvent is preferably containedin such an amount that there is no danger of inflammation, evaporationand the like and there is no problem on safety in handling, for example,on toxicity. Specifically, the amount is preferably 50% by weight orless, more preferably 30% by weight or less.

The pH of the coating liquid is selected appropriately depending on thekind of the compound used. When the adjustment of pH is required, anacid or an alkali compound may appropriately be used as a pH adjuster.The acid is exemplified by hydrochloric acid, sulfuric acid and nitricacid. The alkali compound is exemplified by alkali metal compounds suchas LiOH, NaOH, KOH, Na₂CO₃, Na₂HPO₄ and NH₄OH.

The component (A) in the coating liquid may preferably be in aconcentration ranging from 0.5 to 20.0% by weight, and more preferablyfrom 1.0 to 10.0% by weight. If this component is in too low aconcentration, a difficulty may occur such that the steam must be usedin a large quantity in order to form the coating film in an effectivequantity. If it is in too high a concentration, the coating liquid maybecome unstable to cause a precipitate during storage in a storage tank,and the coating film formed by coating the coating liquid on the innerwall surfaces and others may have uneven coatings to cause a lowering ofthe scale preventive effect.

The proportion of the component (B) to the component (A) may preferablybe 1 to 500 parts by weight, and more preferably 10 to 300 parts byweight, based on 100 parts by weight of the component (A).

The component (A) and the component (B) may preferably be in a totalconcentration ranging from 1.0 to 25.0% by weight, and more preferablyfrom 1.5 to 15.0% by weight.

To the coating liquid, in addition to the components (A) and (B), awater-soluble polymeric compound, a surface-active agent, across-linking agent and so forth may be added in such an extent thatstorage stability, adhesion to wall surfaces and uniform-film-formingproperties of the coating liquid are not damaged or the effect of thepresent invention is not damaged.

[Carrier Steam]

According to the process of the present invention, the coating film isformed by applying the coating liquid on the polymerization vessel innerwall by means of steam as a carrier. The steam used may be steam usuallyavailable or superheated steam, and may preferably be steam having apressure of from 2 to 35 kgf/cm²·G (0.20 to 3.43 MPa·Gauge), and morepreferably one having a pressure of from 2.8 to 20 kgf/cm²·G (0.27 to1.96 MPa·Gauge). The steam may preferably have a temperature of from 120to 260° C., and more preferably form 130 to 200° C.

The pressure and temperature of the steam described above are the valuesmeasured before the mixing of the steam with the coating liquid, forexample, in the interior of a steam feed line 6 as shown in FIG. 1described below.

[Formation of Coating Film]

The coating film formed by the method of the present invention will bedescribed with reference to a coating apparatus shown in FIG. 1, whichillustrates the arrangement in a polymerization apparatus.

Step 1. (Pre-heating of polymerization vessel inner wall surfaces andothers by steam)

Hot water or the like is passed through a jacket 2 attached to apolymerization vessel 1 to pre-heat the polymerization vessel inner wallsurfaces to a temperature of 50° C. or above (preferably from 50 to 95°C.). At the upper part of this polymerization vessel, a coating ring 4is provided which is formed of a ring-shaped pipe and has upward nozzles3 b and downward nozzles 3 a. To the coating ring 4, a line 5 isconnected through which the steam and the coating liquid are fed fromthe outside of the polymerization vessel 1. To the line 5, a steam feedline 6 and the coating liquid feed line 7 are connected through therespective valves. If necessary, the steam (usual steam or superheatedsteam) may be blown into the vessel from the coating nozzles 3 a and 3 bof this coating ring 4 to pre-heat also baffles (not shown) and stirringblades (not shown). In this apparatus, the steam is fed to the coatingring 4 from a steam feeder 8 via a flowmeter 9 through lines 6 and 5.

Step 2. (Coating of coating liquid)

The steam is fed to the coating ring 4, and the coating liquid held in acoating liquid tank 10 is fed to the coating ring 4 through lines 7 and5 by means of a pump 11 or an aspirator valve (not shown). P denotes apressure g auge. The coating liquids is carried by the steam and is, inthe state of mist, applied to and coated on polymerization vessel innerwall surfaces and surfaces with which polymers come into contact duringpolymerization, such as baffle surfaces and stirring blade surfaces.Simultaneously with this coating, a mixture and/or reaction product ofthe first and second coating liquids coated on these surfaces is dried(simultaneous drying), so that the coating film is formed. Hence, it isunnecessary to make any particular operation for the drying.

The steam (G) and the coating liquid (L) may preferably be in a mixingratio (L/G) of from 0.005 to 0.8, and more preferably from 0.01 to 0.2in terms of flow rate ratio on the basis of weight.

Step 3. (Water washing)

After the feeding of the steam and the coating liquid are stopped, theinside of the polymerization vessel is washed with cleaning water heldin a water tank 12. The cleaning water is fed into the polymerizationvessel 1 from nozzles 15 through a line 14 by means of a pump 13.However, water washing is unnecessary if the coating liquid does not soaffect the product quality.

The coating film thus formed may preferably have a dried coating weightof from 0.0005 to 3 g/m², and more preferably from 0.0005 to 1 g/m².

Polymerization

The process of the present invention is applied to the polymerization ofa monomer having an ethylenically unsaturated double bond. Examples ofthe monomer include vinyl halides such as vinyl chloride; vinyl esterssuch as vinyl acetate and vinyl propionate; acrylic acid, methacrylicacid and their esters or salts; maleic acid, fumaric acid and theiresters or anhydrides; diene monomers such as butadiene, chloroprene andisoprene; styrene; acrylonitrile; vinylidene halides; and vinyl ether.

Examples particularly suitable for practicing the process of the presentinvention include the production of polymers of vinyl halides, such asvinyl chloride, vinylidene halides, or a monomeric mixture comprisedprimarily of them by suspension polymerization or emulsionpolymerization in an aqueous medium. The coating film formed by theprocess of the present invention has a high durability even formonomers, such as α-methylstyrene, acrylic acid esters, acrylonitrileand vinyl acetate, which have a high solvency power for the conventionalcoating film, so that the process can be carried out suitably even forthe production of polymer beads and latex comprised of polystyrene,polymethacrylate, polyacrylonitrile, etc.; the production of syntheticrubbers such as SBR, NBR, CR, IR, IIR, etc.(these synthetic rubbers aregenerally produced by emulsion polymerization); and the production ofABS resin.

In the polymerization of one or more of these monomers, an object ofpreventing scale can be effectively accomplished irrespective ofpolymerization types, such as suspension polymerization, emulsionpolymerization, bulk polymerization and solution polymerization, even inthe presence of any of additives such as emulsifiers, stabilizers,lubricants, plasticizers, pH adjusters and chain transfer agents. Forexample, in the case of suspension polymerization or emulsionpolymerization of a vinyl monomer, various additives are optionallyadded, as required. The additives include, for example, suspendingagents such as partially saponified polyvinyl alcohol and methylcellulose; anionic emulsifiers such as sodium lauryl sulfate; nonionicemulsifiers such as sorbitan monolaurate and polyoxyethylene alkylether; stabilizers such as tribasic lead sulfate, calcium stearate,dibutyltin dilaurate and dioctyltin mercaptide; chain transfer agentssuch as trichloroethylene and mercaptans; and pH adjusters. According tothe present process, deposition of scale is effectively prevented in thepresence of any of the additives above.

The remarkable polymer scale deposition preventive effect of theinvention is exhibited without being affected by the kind ofpolymerization catalysts even when any of catalysts is used.Specifically, the catalysts include, for example, t-butylperoxyneodecanoate, bis(2-ethylhexyl)peroxydicarbonate,3,5,5-trimethylhexanoyl peroxide, α-cumyl peroxyneodecanoate, cumenehydroperoxide, cyclohexanone peroxide, t-butyl peroxypivarate,bis(2-ethoxyethyl)peroxydicarbonate, benzoyl peroxide,diisopropylbenzene hydroperoxide, lauroyl peroxide, 2,4-dichlorobenzoylperoxide, diisopropyl peroxydicarbonate, α,α′-azobisisobutylonitrile,α,α′-azobis-2,4-dimethylvaleronitrile, di-2-ethylhexyldiperoxyisophthalate, potassium persulfate and ammonium persulfate.

Other conditions for polymerization may be those which areconventionally used, and there are no limitations unless the effects ofthe present invention are impaired. In the following, taking the casesof suspension polymerization, solution polymerization and bulkpolymerization as examples, typical conditions of polymerization will bedescribed.

First, in the suspension polymerization, water and a dispersant arecharged into a polymerization vessel, and then a polymerizationinitiator is charged therein. Subsequently, the polymerization vessel isevacuated to reduce the initial pressure to a value of 0.1 to 760 mmHg(0.01 to 101 kPa), and a monomer or monomers are then charged, whereuponthe internal pressure takes usually a value of 0.5 to 30 kgf/cm²·G (150to 3,040 kPa). Thereafter, polymerization is carried out at a reactiontemperature of 30 to 150° C. During the polymerization, one or morematerials selected from water, a dispersant and a polymerizationinitiator are, optionally, added. Reaction temperature during thepolymerization is different depending on the kind of a monomer to bepolymerized. For example, in the case of polymerizing vinyl chloride,polymerization is carried out at 30 to 80° C., while in the case ofpolymerizing styrene, polymerization is carried out at 50 to 150° C. Thepolymerization may be judged to be completed when the pressure insidethe polymerization vessel has dropped to a value of 0 to 7 kgf/cm²·G(100 to 790 kPa) or when there has been observed substantially nodifference between the inlet temperature and outlet temperature of acooling water flowing into and out of a jacket providedcircumferentially of the polymerization vessel (i.e., when liberation ofheat due to the polymerization reaction has subsided). The amounts ofthe water, dispersant and polymerization initiator are generally 20 to500 parts by weight, 0.01 to 30 parts by weight, and 0.01 to 5 parts byweight, respectively, per 100 parts by weight of the monomer.

In solution polymerization, an organic solvent, such as toluene, xyleneand pyridine, is used as the polymerization medium, in place of water.If necessary, a dispersant may be used. The other conditions forpolymerization are generally the same as those described for suspensionpolymerization.

In bulk polymerization, after a polymerization vessel is evacuated to apressure of about 0.01 to 760 mmHg (0.001 to 101 kPa), a monomer and apolymerization initiator are charged into the polymerization vessel, andthen polymerization is carried out at a reaction temperature of −10 to250° C. For example, the reaction temperature is 30 to 80° C. for thepolymerization of vinyl chloride, and is 50 to 150° C. for thepolymerization of styrene.

EXAMPLES

The present invention will now be described below in greater detail bygiving Examples. In the following, “part(s)” refers to “part(s) byweight”. In tables, “auxiliary agent” refers to “polymer scalepreventive auxiliary agent”.

Production of Condensation Products

In the following Production Examples, the weight-average molecularweight of each condensation product obtained was measured in thefollowing way.

Measurement of weight-average molecular weight

Weight-average molecular weight in terms of polystyrene was measured bygel permeation chromatography (GPC) under the following measurementconditions.

Columns:

Guard column:

Trade name: Shim-pack GPC-800DP, manufactured by Shimadzu Corporation.

Analytical columns:

Trade name: shim-pack GPC-803D, 802D, manufactured by ShimadzuCorporation.

Mobile phase: 10 mM LiBr/DMF

Flow rate: 1.0 ml/min

Detector: RI

Temperature: 60° C.

Production Example 1

Production of Condensation Product No. 1:

With reference to Production Example 3 disclosed in Japanese PatentPublication (kokoku) No. 6-62709, a scale preventive agent was produced.

Into a pressure-resistant reaction vessel, 30 mols (5.59 kg) of2,2′-dihydroxybiphenyl, 30 mols (0.948 kg) of paraformaldehyde with apurity of 95%, 0.19 kg of paratoluenesulfonic acid and 10 liters ofethylene glycol dimethyl ether were charged, and the temperature wasraised to 130° C. with stirring. After the reaction was carried out at130° C. for 17 hours, the reaction mixture was cooled to 50° C. and thenput into 50 liters of water. The resin separated by putting said mixtureinto water was filtered off and then washed with water, followed bydrying to obtain 5.1 kg of a 2,2′-dihydroxybiphenyl-formaldehydecondensation resin (Condensation Product No. 1). The CondensationProduct No. 1 had a weight-average molecular weight of 5,400.

Production Example 2

Production of Condensation Product No. 2:

With reference to Production Example 1 disclosed in JapanesePre-examination Patent Publication (kokai) No. 57-164107, a polymerscale preventive agent was produced.

Into a pressure-resistant reaction vessel, 250 mols (36.0 kg) of1-naphthol and 180 liters of 1N-NaOH aqueous solution (containing 180mols or 7.2 kg of NaOH) were charged, and the temperature was raised to70° C. with stirring. Next, to the reaction mixture, formaldehyde (19.75liters of 38 w/v % aqueous solution, 250 mols) was dropwise added over aperiod of 1.5 hours. During the addition, the internal temperature ofthe reaction vessel was controlled so as not to exceed 80° C. Then, thereaction mixture was cooled to 60° C. over a period of 3 hours with thestirring kept. Next, the temperature of the reaction mixture was raisedto 98° C. to carry out the reaction at 98° C. for 1.5 hours. Thereafter,the reaction mixture was cooled to obtain an alkaline solution of acondensation product (Condensation Product No. 2). The CondensationProduct No. 2 had a weight-average molecular weight of 2,400.

Production Example 3

Production of Condensation Product No. 3:

With reference to Coating Compound Synthesis 2 disclosed in JapanesePre-examination Patent Publication (kokai) No. 57-192413, a scalepreventive agent was produced.

Into a pressure-resistant reaction vessel, 100 mols (12.6 kg) ofpyrogallol and 100 liters of water were charged, and the pyrogallol wasdissolved in the water. Next, to the solution obtained, 200 mols (21.2kg) of benzaldehyde and 300 mols (29.4 kg) of phosphoric acid wereadded, and the mixture thereof was reacted at 95° C. for 10 hours. As aresult, a water-insoluble reddish brown product was obtained. Thiswater-insoluble product was washed with ether, followed by extractionwith methanol to extract a methanol-soluble matter from thewater-insoluble product. Then, the methanol was removed from the extractby drying to obtain Condensation Product No. 3 (pyrogallol-benzaldehydecondensate), as a residue. The Condensation Product No.3 had aweight-average molecular weight of 4,500.

Production Example 4

Production of Condensation Product No. 4:

With reference to Production Example 1 disclosed in JapanesePre-examination Patent Publication (kokai) No. 54-7487. a scalepreventive agent was produced.

Into a reaction vessel, 200 mols (22.0 kg) of resorcinol was charged,and then heated in a nitrogen atmosphere. The temperature of resorcinolwas raised to 300° C., and the reaction was carried out at 300° C. for 8hours, followed by cooling. The solid self-condensed resorcinol(Condensation Product No. 4) thus obtained was pulverized. TheCondensation Product No. 4 had a weight-average molecular weight of1,700.

Production Example 5

Production of Condensation Product No. 5:

(1) Synthesis of a 2,3-dihidoroxynaphthalene dimer compound

Into a flask having an inner capacity of 3 liters provided with a refluxcondenser, 1350 mL of methanol was charged and then 144g (0.9 mol) of2,3-dihydoroxynaphthalene was dissolved therein. After the dissolution,the temperature was raised to 65° C., and 243 g (0.9 mol) of ferricchloride hydrate(FeCl₃.6H₂O) dissolved in 450 mL of methanol was addeddropwise to the solution obtained under reflux over 30 minutes. Afterthe addition, reaction was continued under reflux for 5 hours.Subsequently, the reaction solution was transferred into 4.5 liters of adiluted hydrochloric acid and then the resulting mixture was stirred for12 hours, to produce a dimer compound of 2,3-dihydroxynaphthalene. Thereaction solution thus obtained was filtered to remove the solvents, andthereafter the residual matter was washed with two liters of pure waterfor two hours. The solution was filtered again to remove the ferricchloride hydrate(FeCl₃. 6H₂O).

The dimer compound of 2,3-dihydroxynaphthalene obtained was dried in adryer at 40° C.,

(2) Into a 3 liter-flask provided with a reflux condenser, one liter ofpure water was charged, and then 5 g of sodium hydroxide and 50 g of the2,3-dihydroxynaphthalene dimer compound obtained as above were charged.Subsequently, after the temperature was raised to 70° C., 12.75 g of 37%aqueous formaldehyde solution dissolved in 237.3 g of distilled water,was added dropwise over 30 minutes. After the addition, reaction wascontinued at the same temperature for five hours, and then thetemperature was raised to 95° C. and reaction was continued for furthertwo hours, thereby Condensation Product No. 5 being obtained.Incidentally, the reactions were all carried out in N₂ atmospheres.

After the completion of the reactions, Condensation Product No. 5 wascooled to 25° C., and then preserved in an N₂ atmosphere. Theweight-average molecular weight was 22,000.

Production Example 6

Production of Condensation Product No. 6:

Into a reaction vessel having an inner capacity of 2 liters providedwith a reflux condenser, a mixed solvent of methanol (450 g) with water(450 g) was charged and subsequently 100 g of α-naphthoquinone and 10 gof sodium hydroxide were charged. Then, the internal temperature of thereaction vessel was raised to 50° C. and the mixture in the reactionvessel was reacted at 50° C. for 24 hours, followed by cooling the sameto room temperature. Thus, a solution of Condensation Product No.6 wasobtained. The Condensation Product No. 6 had a weight-average molecularweight of 3,000.

Production Example 7

Production of Condensation Product No. 7:

In a 20 L internal volume reaction vessel having a reflux condenser, 1.5kg of 1-naphthol and 7.5 L of toluene were put, and the mixture obtainedwas heated with stirring until the toluene became refluxed. Under refluxat this temperature, 930 ml of sulfur monochloride was added dropwiseover a period of 6 hours, and thereafter the mixture obtained was keptfor 1 hour at that temperature. After the reaction mixture was cooled, 5L of hexane was added with stirring to cause the reaction product toprecipitate. Thereafter, the reaction product was filtered, and thendried to obtain Condensation Product No. 7. The Condensation Product No.7 had a weight-average molecular weight of 1,200.

Production Example 8

Production of Condensation Product No. 8:

In a 20 L internal volume reaction vessel having a reflux condenser, 6.7L of water, 1,786 g (9.5 mols) of 6-hydroxy-2-naphthoic acid, 55 g (0.5mol) of resorcinol and 620 g (15.5 mols) of NaOH were put, andthereafter the mixture obtained was heated to 50° C. with stirring. Atthe time it reached 50° C., 1.0 L of an aqueous 30 w/v % formaldehydesolution (formaldehyde: 10 mols) was added dropwise over a period of 1hour. During the addition, the internal temperature of this reactionvessel was so controlled not to become higher than 55° C. Next, thereaction mixture thus obtained was heated to 85° C., and was allowed toreact at 85° C. for 3 hours. Thereafter, the reaction mixture obtainedwas cooled to obtain an alkaline solution of a condensation product(Condensation Product No. 8). The Condensation Product No. 8 had aweight-average molecular weight of 2,200.

Preparation of Coating liquids

Preparation of coating liquid Nos.101-129:

Using a conjugated π C bond compound, an inorganic colloid, a chelatereagent, a metal compound that produces a metal ion capable of forming acomplex having at least two coordination numbers, an acid, a pH adjusterand a solvent which are shown in Tables 1A and 1B and Tables 2A and 2B,coating liquids were so prepared as to meet the conditions shown inTables 1A and 1B and Tables 2A and 2B [conjugated π bond compound (A),auxiliary agent (B), pH adjuster, (A)/(B)-i/(B)-ii/(B)-iii/(B)-iv weightratio, (A)+(B) total concentration, solvent composition, and pH].

Incidentally, the coating liquid No. 102 is a coating liquid containinga scale preventive agent in a low concentration, to be used for spraycoating. Coating liquids Nos. 103, 104, 105, 106, 107, 108, 109 and 110are coating liquids containing a conventional steam coating scalepreventive agent to which the component (B) is not added.

Preparation of coating liquid Nos. 130-134:

The following compounds I to V were used as a conjugated π bondcompound.

I: 3,6-Diaminoacrydine

II: Phenanthrene-1,4-quinone

III: Quinizarine

IV: 1,8-Diaminoanthrathene

V: Flavonol

Using a compound above, a pH adjuster and a solvent shown in Tables 2Aand 2B, coating liquids were so prepared as to meet the conditions shownin Tables 2A and 2B [conjugated π bond compound (A), auxiliary agent(B), pH adjuster, (A)/(B)-i/(B)-ii/(B)-iii/(B)-iv weight ratio, (A)+(B)total concentration, solvent composition, and pH].

In the following table, the condensation product is simply called “CP”.For example, “CP1” stands for “Condensation Product No. 1”.

TABLE 1A Auxiliary agent(B) Metal compound that produces metal ioncapable of Conju- forming complex Ex- gated π Inor- having at peri- bondganic least two ment pound colloid Chelate coordination Acid No. (A) (1)agent (2) numbers (3) (4) 101 CP6 none thiourea calcium phitc acidpyrophosphate 102* CP6 colloi- none none none dal silica 103* CP1 — — —— 104* CP2 — — — — 105* CP3 — — — — 106* CP4 — — — — 107* CP5 — — — —108* CP6 — — — — 109* CP7 — — — — 110* CP8 — — — — 111 CP1 colloi- — — —dal sil- ica 112 CP2 — diethylene- — — triamine 113 CP3 — — pyrophos- —phoric acid calcium 114 CP4 — — — pyrophos- phoric acid 115 CP5 colloi-imidazole — — dal sil- ica 116 CP6 colloi- — nickel chloride — dal sil-ica 117 CP7 colloi- — — poly- dal sil- phos- ica phoric acid 118 CP8colloi- — — — dal sil- ica

TABLE 1B (A)/(B)- i/(B)- (A) + (B) ii/(B)- Total iii/(B)-iv concen-Experiment Weight tration pH No. ration (wt %) Solvent adjuster pH 101100/-/ 5.0 water/ NaOH 12.0 10/10/10 methanol/ (60/40) 102* 100/100/-/-0.5 water NaOH 10.5 /- 103* 100/- 5.0 water NaOH 12.0 104* 100/- 5.0water NaOH 12.0 105* 100/- 5.0 water NaOH 12.0 106* 100/- 5.0 water NaOH12.0 107* 100/- 5.0 water NaOH 12.5 108* 100/- 5.0 water NaOH 12.5 109*100/- 5.0 water NaOH 12.5 110* 100/- 5.0 water NaOH 12.5 111 100/100/-/-4.0 water NaOH 12.5 /- 112 100/-/30/- 5.0 water/ethanol KOH 12.0 /-(60/40) 113 100/-/-/ 3.0 water KOH 12.0 20/- 114 100/-/-/50 4.0 water —3.0 115 100/100/ 6.5 water NaOH 9.0 30/-/- 116 100/100/-/ 5.0 water NaOH8.0 30/- 117 100/100/-/- 8.5 water/methanol — 2.5 /50 (70/30) 118100/50/-/- 5.0 N-methyl- — — /- 2-pyrrolidone

TABLE 2A Auxiliary agent(B) Metal compound that produces metal ioncapable of Conju- forming complex Ex- gated π Inor- having at peri- bondganic least two ment pound colloid Chelate coordination Acid No. (A) (1)agent (2) numbers (3) (4) 119 CP1 — dithizone — tannic acid 120 CP2 —8-hydroxy- — phitic acid quinoline 121 CP3 — — titanium sulfate — 122CP4 — — calcium phitic acid phosphate 123 CP5 — imidazole — terephtha-lic acid 124 CP6 — trieth- copper sulfunilic ylene- sulfate acid tetra-mine 125 CP7 — 1,3-diamino- cobalt chloride — propane 126 CP8 — thiourea— poly- phospho- ric acid 127 CP6 — — calcium salicylic carbonate acid128 CP6 — thiooxine boron oxide — 129 CP6 — triethylene- ferric —tetramine sulfate 130 I — thiourea calcium pyro- — phophate 131 II —trieth- ferric — ylene- sulfate tetramine 132 III — imidazole — phiticacid 133 IV — diethyl- — phitic acid enetriamine 134 V — 1,3-diamino- —pyro- propane phospho- ric acid

TABLE 2B (A)/(B) i/(B)- (A) + (B) ii/(B)- Total iii/(B)-iv concentra-Experiment Weight tion pH No. ration (wt %) Solvent adjuster pH 119100/-/ 2.0 water/ — 6.0 10/-/10 methanol/ (60/40) 120 100/-/10/- 5.5water NaOH 11.0 /20 121 100/-/-/5/- 4.0 water KOH 7.5 122 100/-/-5/5 5.0water sulfate 4.0 123 100/-/5/-/40 5.0 water NaOH 12.0 124 100/-/5/10/55.0 water KOH 11.0 125 100/-/10/ 5.0 water KOH 11.0 10/20/- 126100/-/30/- 5.0 water NaOH 10.0 /10 127 100/-/- 7.0 N-methyl-2- — —/10/20 pyyrolidone 128 100/- 7.5 water NaOH 11.5 /10/20/- 129 100/- 5.0water NaOH 11.0 /20/10/- 130 100/-/20/5/- 5.0 water NaOH 9.5 131100/-/50/5/- 5.0 water/ NaOH 12 methanol (60/40) 132 100/-/20/- 5.0water NaOH 12 /10 133 100/-/20/- 5.0 N-methyl-2- — — /20 pyyrolidone 134100/-/10/- 5.0 water — 2.5 /30

Example 1

FIG. 2 schematically illustrates the arrangement of a polymerizationapparatus. In respect to a polymerization vessel, the same elements asin FIG. 1 are denoted with the same numerals. The following experimentswere made using a polymerization apparatus shown in FIG. 2. In FIG. 2, a2 m³ nal volume polymerization vessel 1 made of SUS 316L stainless steelis equipped with a stirrer 21 having stirring blades 20 (a stirringmotor is not shown), a heating-cooling jacket 2, a manhole 22, a baffle23 and other fittings (not shown) usually providing for polymerizationvessels for polymerizing vinyl chloride. A line 24 connected to theupper part of the polymerization vessel 1 is a line for chargingmaterials. To the line 24, branch lines such as a vinyl chloride monomer(VCM) charging line 24 a, a catalyst solution charging line 24 b, asuspending agent charging line 24 c and a pure-water charging line 24 dare connected as shown in FIG. 2. This charging lines 24 and 24 a-24 dare provided with valves V1, V2, V3, V4 and V5 at the positions shown inthe drawing. A line 25 also connected to the upper part of thepolymerization vessel 1 is provided in order to evacuate the inside ofthe polymerization vessel 1 and to recover monomers, and is led to a gasholder 27 through a line 26 branched from the line 25. A monomerrecovery line 28 is led out of the gas holder 27, and a line 29 led outof the gas holder 27 is connected to the line 25 so as to be used inpressure equalization described later. These lines 25, 26, 28 and 29 areprovided with valves V6, V7, V8, V9, V10, V11, V12 and V13. The line 26is branched into a line 26 a provided with a vacuum pump 30 so thatmonomers can be recovered and a line 26 b with no pump, and thereafterthe branched lines are joined together to form a single line which isconnected to the gas holder 27. To the upper part of the polymerizationvessel 1, a line 31 is also connected in order to wash the inside of thepolymerization vessel with water. The line 31 is provided with a valve14 at the position shown in the drawing and has a nozzle 32 at the endintroduced inside the vessel. To the upper part of the polymerizationvessel 1, a coating liquid feed line 34 is connected to a coating liquidfeed line 33 through a valve V17 as shown in the drawing. Further, tothe line 33 a steam feed line 35 is connected via a valve V18. The line33 is provided at its end located inside the vessel with a coating ring4 to which coating nozzles 3 a, 3 b are attached. The line 33 isprovided with valves V15 and V16 at the positions shown in the drawing.To the bottom of the polymerization vessel 1, a line 36 is connected,which is branched into a line 37 a through which polymer slurry is ledto a blow-down tank and a line 37 b through which the coating liquids orwashing water is discharged. These lines 36, 37 a and 37 b are providedwith valves V19, V20 and V21 at the positions shown in the drawing.

Reference Nos. of coating liquids used in each experiment are shown inTables 4 and 5. The coating liquids were previously coated on thepolymerization vessel inner wall surfaces and others in the manner asdescribed below, followed optionally by drying to form a coating film.In the polymerization vessel, vinyl chloride monomers were polymerizedin the manner as described below.

(1) Coating and drying:

The coating film is formed on the inner wall surfaces and others of thepolymerization vessel of the polymerization apparatus shown in FIG. 2,by a method of a), b), c) or d) below. Methods a), b) and c) are methodsof comparative examples. In the initial stage of each method, all of thevalves are closed.

a) One-liquid spray coating and drying:

Hot water is passed through the jacket 2 to keep the polymerizationvessel 1 inner wall surfaces heated to a temperature of 70° C. (Time forpreheating with the jacket: 10 minutes). The valves V17, V16, V15, V19and V21 are opened, and the coating liquid is coated at a flow rate of 5L(liter)/min for 1.5 minutes. The valves V17, V16, V15, V19 and V21 areclosed, and then the valves V6, V8, V13, and V9 are opened, where thevacuum pump 30 is actuated to evacuate the inside to 8.0 kPa (−700 mmHgand the wet coating is dried (drying is necessary; drying time: 25minutes) to form a coating film. Thereafter, the vacuum pump is stoppedand the valves V8, V13, and V9 are closed. Next, the valves V7 and V10are opened to make the internal pressure of the polymerization vessel 1equal to the internal pressure of the gas holder 27. Thereafter, thevalves V6, V7 and V10 are closed. The feeding of hot water to the jacket2 is stopped.

b) Steam coating (and simultaneous drying):

Hot water is passed through the jacket 2 to keep the polymerizationvessel 1 inner surfaces heated to a temperature of 70° C. (Time forpreheating with the jacket: 10 minutes). The valves V18, V21, V19, V15and V16 are opened, and 392 kPa·Gauge (4 kg/cm²·G) (143° C.) of steam isblown into the polymerization vessel at a flow rate of 240 kg/Hr for 3minutes. After the inside of the vessel is pre-heated, the valve V17 isopened, and the coating liquid containing a scale preventive agent iscoated and dried simultaneously at a flow rate of 0.2 L/min for 2minutes while utilizing the steam as a carrier. Thereafter, the valvesV18, V21, V19, V15, V16 and V17 are closed. The feeding of hot water tothe jacket 2 is stopped.

(2) Second water washing for inside of the vessel:

The valves V14, V19, V21, V6, V7 and V10 are opened to wash the insideof the polymerization vessel with water, and the wash water isdischarged to a waste water tank. The valves V14, V19 and V21 areclosed.

The time for washing with water is four (4) minutes when the method a)or b) is used, and it is one (1) minute when the method c) or d) isused.

(3) Charging:

The valves V1, V2 and V3 are opened, and 200 parts by weight of purewater, 0.022 part by weight of partially saponified polyvinyl alcoholand 0.028 part by weight of hydroxymethyl cellulose are charged into thepolymerization vessel 1. The valves V1, V2, V3, V6, V7 and V10 areclosed.

Next, the valves V1 and V5 are opened, and 100 parts by weight of vinylchloride monomer (VCM) is charged. Then the valve V5 is closed. Next,with the charged materials being stirred, the valve V4 is opened, and0.03 part by weight of t-butyl peroxyneodecanate is charged. Then thevalves V1 and V4 are closed.

(4) Polymerization:

Hot water is passed through the jacket 2 to raise the temperature whilestirring the materials charged. At the time the internal temperature hasreached 52° C.,cooling water is passed through the jacket 2 to maintainthe internal temperature at 52° C., where the polymerization is carriedout. At the time the internal pressure has dropped to 490 kPa·Gauge (5kg/cm²·G), the polymerization is terminated.

(5) Gas discharging:

The valves V6, V8, V12 and V9 are kept open, and gas is discharged tothe gas holder 27 until the internal pressure returns to substantiallythe atmospheric pressure. Thereafter, the valves V12, V8 and V9 areclosed. Then the valves V11 and V10 are opened, and monomers recoveredin the gas holder 27 is sent to the step of recovering the VCM throughline 28. Thereafter, the valves V11 and V10 are closed.

(6) Pressure equalization:

The valves V7 and V10 are opened, and the internal pressure of thepolymerization vessel 1 and the internal pressure of the gas holder 27are made equal (pressure equalization).

(7) Slurry withdrawing:

The valves V19 and V20 are opened, and polymerization slurry iswithdrawn out of the vessel to the blow-down tank (not shown). Thepolymerization slurry withdrawn to the blow-down tank is thereafterdehydrated and dried to become a vinyl chloride polymer product.

(8) Vessel-inside first washing:

The valve V14 is opened. The inside of the polymerization vessel 1 iswashed with water, and the wash water is sent to the blow-down tank.Thereafter, the valves V14, V19, V21, V6, V7 and V10 are closed. Duringthis washing of the inside of the vessel, hot water is passed throughthe jacket 2 to keep the temperature of the polymerization vessel wallsurfaces at 70° C.

The operation from the (1) coating and drying up to the (8) firstwashing after completion of polymerization is set as one batching. Thelike operation was repeated by the number of batching as shown in Tables4 and 5.

<Evaluation>

Time required to form coating films

The time taken for the formation of coating films in Examples andComparative Examples is shown in Table 3.

Measurement of the amount of polymer scale deposited

In each experiment, after the final batching was completed, polymerscale built-up at the liquid-phase portion in the polymerization vesseland polymer scale built-up on the surfaces of stirring blades andbaffles and on and in the vicinity of the boundary between the gas-phaseportion and the liquid-phase portion were determined in the followingway.

The scale deposited in an area of 10 cm×10 cm at a surface to bemeasured was scraped off with a spatula as completely as can beconfirmed with the naked eye, and. then the scraped scale was weighed ona balance. The measured value was multiplied by 100 to obtain the amountof the deposited polymer scale per area of 1 m². The results are givenin Tables 4 and 5.

Measurement of fish eyes

Fish eyes produced when a polymeric product obtained at the finalbatching in each experiment is formed into sheet, were measured by themethod below. The results are given in Tables 5 and 6.

A hundred (100) parts by weight of a polymer obtained, 50 parts byweight of dioctyl phthalate (DOP), 1 part by weight of dibutyltindilaurate, 1 part by weight of cetyl alcohol, 0.25 part by weight oftitanium oxide and 0.05 part by weight of carbon black were mixed. Theresulting mixture was kneaded at 150° C. for 7 minutes with 6 inchrolls, and then formed into a sheet 0.2 mm thick. The obtained sheet wasexamined for the number of fish eyes per 100 cm² by light transmission.

Measurement of luminosity index (L value)

Measurement of luminosity index (L value) of a sheet formed from apolymer obtained in each experiment was carried out, according to themethod below. The results are given in Tables 5 and 6.

A hundred (100) parts by weight of an obtained polymer, 1 part by weightof a dibutyltin laurate stabilizing agent (TS-101, product of AkisimaChemical Co.) and 0.5 part by weight of a cadmium organic complexstabilizing agent (C-100J, product of Katsuta Kako Co.), and 50 parts byweight of dioctyl phthalate as a plasticizer were kneaded at 160° C. for5 minutes with a twin roll mill, and then formed into a sheet 1 mmthick. Subsequently, this sheet was placed in a molding frame measuring4×4×1.5 cm, heated at 160° C. under a pressure of 6.37 to 6.87 MPa·Gauge(65 to 70 kgf/cm²·G) to prepare a test specimen. This test specimen wasmeasured for luminosity index L in the following way.

First, the stimulus value Y of XYZ color system is determined by thephotoelectric tristimulus colorimetry using the standard light C,photoelectric colorimeter (Color measuring color difference meter ModelZ-1001DP, product of Nippon Denshoku Kogyo K.K.) in accordance with JISZ 8722. As the geometric condition of illumination and light reception,the condition d defined in section 4.3.1 of JIS Z 8722 is adopted.

Next, from the stimulus value Y obtained, the L value is calculatedbased on the Hunter's color difference equation: L=10Y^(1/2) describedin JIS Z 8730 (1980). The greater the value of L, the higher thewhiteness is evaluated, namely, the better the initialanti-discoloration properties are.

Examination of colored particles:

A mixture of 100 parts by weight of the polymer obtained in eachexperiment after the final batching was completed, 2 parts by weight ofa stabilizer TVS N-2000E (available from Nitto Kasei Co., Ltd.) and 20parts by weight of a plasticizer dioctyl phthalate was thoroughlykneaded and thereafter put in a molding frame of 160 mm×130 mm×3 mm, andwas subsequently pressure-molded at a temperature of 175° C. and apressure of 3.43 MPa·Gauge(35 kgf/cm²·G) to obtain a sample forexamination. Samples thus obtained were examined visually on the numberof colored particles. The results are shown in Tables 5 and 6.

TABLE 3 a) Spray coating b) Steam coating Jacket pre-heating time (min)10.0 10.0 Steam pre-heating time (min) 0 3.0 Coating time (min) 1.5 2.0Drying time (min) 25.0 0 Water washing time (min) 4.0 1.0 (secondwashing) Total time (min) 40.5 16.0

TABLE 4 Scale build-up (g/m²) Vicinity Coating Number Liquid of gas-Experiment Coating liquid of phase liquid Stirring No. film formationNo. batches portion interface blade Baffle 101  b) Steam coating 101 3000  0  0  0 102* a) Spray coating 102 300 0  0 125  135  103* b) Steamcoating 103 300 0 126 28 30 104* b) Steam coating 104 300 0 111 18 21105* b) Steam coating 105 300 0 108 17 20 106* b) Steam coating 106 3000 122 21 25 107* b) Steam coating 107 300 0 124 24 27 108* b) Steamcoating 108 300 0 105 17 19 109* b) Steam coating 109 300 0 116 20 24110* b) Steam coating 110 300 0 127 25 29 111  b) Steam coating 111 3000  0  2  4 112  b) Steam coating 112 300 0  0  5 10 113  b) Steamcoating 113 300 0  0  2  5 114  b) Steam coating 114 300 0  0  2  5 115 b) Steam coating 115 300 0  0  4  7 116  b) Steam coating 116 300 0  0 3  7 117  b) Steam coating 117 300 0  0  2  4 118  b) Steam coating 118300 0  0  4  8

TABLE 5 Scale build-up (g/m²) Vicinity Coating Number Liquid of gas-Experiment Coating liquid of phase liquid Stirring No. film formationNo. batches portion interface blade Baffle 119 b) Steam coating 119 3000 0 0 0 120 b) Steam coating 120 300 0 0 0 0 121 b) Steam coating 121300 0 0 0 0 122 b) Steam coating 122 300 0 0 0 0 123 b) Steam coating123 300 0 0 0 0 124 b) Steam coating 124 300 0 0 0 0 125 b) Steamcoating 125 300 0 0 0 0 126 b) Steam coating 126 300 0 0 0 0 127 b)Steam coating 127 300 0 0 0 0 128 b) Steam coating 128 300 0 0 0 0 129b) Steam coating 129 300 0 0 0 0 130 b) Steam coating 130 300 0 6 3 12 131 b) Steam coating 131 300 0 7 5 15  132 b) Steam coating 132 300 0 94 10  133 b) Steam coating 133 300 0 8 4 13  134 b) Steam coating 134300 0 8 3 11 

TABLE 6 Colored Experiment Fish eyes Luminosity index particles No.(number) (L value) (number) 101 1 73.0 4 102* 61 72.0 73 103* 19 72.0 58104* 16 72.0 50 105* 14 72.0 49 106* 18 72.0 52 107* 18 72.0 51 108* 1372.0 44 109* 17 72.0 56 110* 19 72.0 61 111 3 73.0 7 112 3 73.0 7 113 473.0 9 114 3 73.0 6 115 4 73.0 8 116 4 73.0 9 117 3 73.0 7 (Remarks)*Comparative Example

TABLE 7 Colored Experiment Fish eyes Luminosity index particles No.(number) (L value) (number) 118 3 73.0 6 119 1 73.0 4 120 1 73.0 5 121 273.0 6 122 1 73.0 5 123 2 73.0 4 124 1 73.0 5 125 1 73.0 4 126 1 73.0 5127 2 73.0 6 128 1 73.0 5 129 1 73.0 4 130 6 72.5 7 131 6 72.5 7 132 572.5 6 133 6 72.5 5 134 7 72.5 6

What is claimed is:
 1. A process for producing a polymer by polymerizingin a polymerization vessel a monomer having an ethylenic double bond,wherein said polymerization vessel has a polymer scale preventivecoating film on its inner wall surfaces and other surfaces with whichthe monomer comes into contact during polymerization; said coating filmbeing formed by coating a coating liquid containing: (A) a compoundselected from the group consisting of an aromatic compound having 5 ormore conjugated π bonds and a heterocyclic compound having 5 or moreconjugated π bonds; and (B) at least one compound selected from thegroup consisting of an inorganic colloid, a chelate reagent, a metalcompound that produces a metal ion capable of forming a complex havingat least two coordination numbers, and an acid; said coating liquidbeing coated by means of steam as a carrier.
 2. The process of claim 1,wherein said conjugated π bond-containing compound contained in thecoating liquid is an aromatic compound condensation product having aweight-average molecular weight of 500 or more.
 3. The process of claim2, wherein said weight-average molecular weight ranges from 500 to70,000.
 4. The process of claim 2, wherein said aromatic compoundcondensation product is selected from the group consisting of aldehydecompound/aromatic hydroxyl compound condensation products,pyrogallol/acetone condensation products, polyhydric phenolself-condensation products, polyhydric naphthol self-condensationproducts, quinone compound condensation products, and sulfide compoundsof aromatic hydroxyl compounds.
 5. The process of claim 2, wherein saidaromatic compound condensation product is an aldehyde compound/aromatichydroxyl compound condensation product or a quinone compoundcondensation product.
 6. The process of claim 1, wherein said coatingliquid is a solution containing a compound selected from the groupconsisting of pyrogallol/acetone condensation products, polyhydricphenol self-condensation products and polyhydric naphtholself-condensation products in water or a mixed solvent of water with ahydrophilic organic solvent miscible with water, and having a pH of 2.0to 6.5.
 7. The process of claim 1, wherein said coating liquid is asolution containing a compound selected from the group consisting ofcondensation products of aldehyde compound/aromatic hydroxyl compound,and condensation products of a quinone compound in water or a mixedsolvent of water with a hydrophilic organic solvent miscible with water,and having a pH of 4 to 13.0.
 8. The process of claim 1, wherein thecomponent (B) comprises a cationic chelate compound having acoordination group selected from the group consisting of an —NH₂ group,an ═NH group, an ≡N group, an —N═N— group, an —NO₂ group, an —N═O group,a ═C═N group, a ═C═NH group, an —S— group, a ═C═S group, an ≡S, an —SCNgroup, a ═C═O group, an —O— group, a —COOR group, an —N═O group and an≡N→O group.
 9. The process of claim 1, wherein the component (B)comprises an anionic chelate compound having a coordination groupselected from the group consisting of an alcoholic hydroxyl group, a—COOH group, an —SO₂H group, an ═N—OH group, an —SH group and a grouprepresented by the formula:


10. The process of claim 1, wherein the component (B) comprises aninorganic colloid selected from the group consisting of colloids ofoxides or hydroxides of metals selected from aluminum, thorium,titanium, zirconium, antimony, tin and iron; colloids of tungstic acid,vanadium pentoxide, selenium, sulfur, silica, gold, silver and silveriodide.
 11. The process of claim 1, wherein the component (B) comprisesa metal compound that produces a metal ion capable of forming a complexhaving 2, 4, 6 or 8 coordination number.
 12. The process of claim 11,wherein said metal compound is a metal compound that produces a metalion selected from the group consisting of Cu(I), Ag(I), Hg(I), Hg(II),Be(II), B(III), Zn(II), Cd(II), Hg(II), Al(III), Co(II), Ni(II), Cu(II),Ag(II), Au(III), Pd(II), Pt(II), Ca(II), Sr(II), Ba(II), Ti(IV), V(III),V(IV), Cr(III), Mn(II), Mn(III), Fe(II), Fe(III), Co(II), Co(III),Ni(II), Pd(IV), Cd(II), Al(III), Sc(III), Y(III), Si(IV), Sn(II),Sn(IV), Pb(II), Pb(IV), Ru(III), Rh(III), Os(III), Ir(III), lanthanoids,Zr(IV), Hf(IV), Mo(IV), W(IV), U(IV) and actinoids.
 13. The process ofclaim 1, wherein the component (B) contains at least one of an inorganicacid and an organic acid.
 14. The process of claim 1, wherein thecomponent (B) is present in an amount of 1 to 500 parts by weight basedon 100 parts by weight of the component (A).
 15. The process of claim 1,wherein the component (A) in said coating liquid is in a concentrationranging from 0.5 to 20.0% by weight.
 16. The process of claim 1, whereinthe component (A) and the component (B) in said coating liquid arepresent in a total concentration of 1.0 to 25.0% by weight.
 17. Theprocess of claim 1, wherein said s team used in the application of saidcoating liquid has a temperature of 120 to 260° C. and a pressure of0.20 to 3.43 MPa·Gauge (2 to 35 kgf/cm²·G).
 18. The process of claim 17,wherein said steam has a temperature of 130 to 200° C. and a pressure of0.27 to 1.96 Mpa·Gauge (2.8 to 20 kgf/cm²·G).
 19. The process of claim1, wherein, in the application of said coating liquid, the coatingliquid (L) and the steam (G) are mixed in a ratio (L/G) of from 0.005 to0.8 in terms of flow rate ratio on the basis of weight.
 20. The processof claim 19, wherein said ratio of L/G is in a range of 0.01 to 0.2.